Many scientific and industrial applications require the presentation of precise, repeatable, and quantifiable olfactory stimuli. Currently, no practical and standardized olfactometer for generating such stimuli is commercially available within the United States. The goal of this program is to develop such a device, with attention paid to ease of operation and serviceability. This instrument will use permeation tubes as the initial odorant source for accurate and stable generation of low- level olfactory stimuli and will employ a photoionization detector to monitor the stimulus concentrations online. Also, the proposed device will use mass flow controllers to insure the maintenance of stable and highly regulated air flows. This system will be versatile in application, easy to operate, and easy to maintain and service. In Phase I of development, the utility of using permeation tubes as a source for olfactory stimuli was investigated. Other major components of the system were evaluated and selected. In Phase II, we will construct a working precision olfactometer. This goal will be achieved in three stages: 1) fabrication of the olfactometer; 2) interfacing to a computer and writing the appropriate software; and 3) thorough evaluation of the instrument, using analytical and organoleptic measures. Operator ergonomics of the olfactometer will also be examined. PROPOSED COMMERCIAL APPLICATIONS: The proposed olfactometer would be applicable where ever there is a need for presentation of precise, well defined olfactory stimuli, e.g., in medicine, basic research, and in government and commercial laboratories working in the field of olfaction.